Cryotherapy is a promising treatment for many conditions. For example, cryosurgery has been used for many years in the treatment of skin cancers. This technology is now being utilized in the treatment of cancers of the liver, prostate, pancreas, and kidney. Although cryotherapy for treatment of prostate cancer dates back to the 1960's, the high rate of complications, such as inadvertent freezing of the rectum which created rectal fistulas between the prostate, the rectum, and the urethra, limited the widespread application of this treatment for many years.
Advances in transrectal ultrasound, the development of computerized instrumentation to control the freezing probes, and the development of wires and tubes have enabled precise cryosurgery leading to renewed interest in cryotherapy treatment of prostate cancer. For example, the border of the freezing zone created during cryotherapy is visible by ultrasound so that the ice ball created in the prostate by the freezing can be seen.
Cryotherapy of the prostate is performed with the patient in the lithotomy position, using an ultrasound imaging probe placed in the rectum to guide an instrument called a cryoprobe and to monitor the freezing of the prostate. Typically, in cryotherapy, liquid nitrogen or a similar freezing agent is circulated through the cryoprobe, which is placed in contact with the tumor. The tumor is frozen as is some of the surrounding tissue. Often, the treatments are cyclic in which the tumor is frozen, allowed to thaw, and then refrozen. The goal of this treatment is to rapidly kill the cancer cells without subjecting the surrounding healthy tissue to trauma.
In order to optimize the cryotherapy treatment, the ultrasound images should accurately reflect the anatomy. A stable liquid interface covering the transducers on the ultrasound probe improves image quality. The present invention is directed to a tissue warming and/or apparatus and method that can be used with these ultrasound transducer covers.